1. Field of the Invention
The present invention relates to an apparatus for assigning programable input-output memory space for an input-output device to be used by incorporating into a computer main unit.
2. Description of the Related Art
In general, in a computer, such as a personal computer, office computer and machinery-equipment computer, in addition to a computer main unit, input-output devices to be used by incorporating in the computer main unit are prepared for the purpose of extending functions for specific usage, such as image processing, communication processing and data collecting. As the input-output device, there is used an adaptor card or I/O board to be connected to an extension slot in a connecting section provided on the side of the computer main unit, from which a system bus and the like are outputted.
Incidentally, when a plurality of adaptor cards is used by incorporating into one computer, in general, separate input-output memory spaces are assigned to the respective adaptor cards. It is generally practiced that an assignment method comprises preparing a switch, for example, a dip switch for designating memory space to be assigned, and comparing contents of the switch and contents of an address bus contained in a system bus. And, at this time, the switch is carefully set so that the memory spaces to be assigned do not become same when a plurality of adaptor cards is incorporated.
However, since the above-mentioned switch for setting the assignment area for the input-output memory space in the adaptor card is different in a type and a setting method for every adaptor cards, when the switch is set, complicated operations referring to an instruction manual are required. More specifically, when an adaptor card is incorporated in a computer in which another adaptor card has already been incorporated, by reason that an instruction manual for setting a switch for the already incorporated adaptor card is unavailable, there has been a disadvantage that the additional adaptor card can not be set therein since a method for setting the switch for the additional adaptor card is not available.
Also, in general, since a switch for an adaptor card is set under a condition that a computer is turned off by reason of security, first, a power source of the computer is turned off, the switch for the adaptor card is set, and then the power source of the computer is again turned on to confirm whether setting of the switch is correctly carried out. If the setting of the switch is wrong, the above operations have to be repeated, resulting in complicated operations requiring much time and labour, and poor workability.
Therefore, in order to solve the above problems, a method for assigning input-output memory space which is programmable in a software, not relying on a switch, has been desired.
Incidentally, as a method for assigning input-output memory space which is programmable in a software, there has been proposed a method, wherein a specific control line is provided to every extension slot and, only when the control line is under an effective operation condition, data is written in a register which performs the same function as setting of a switch.
However, the above-described method is effective for only some computers where a specific signal is assigned to every extension slot, and the method can not be available for a large number of conventional computers which have widely been used.
Therefore, the present invention has been made based on the above-described problems, and is to provide a method and apparatus for assigning input-output memory space, wherein assignment of the input-output memory space can be performed by an extremely simple input operation with respect to all the ordinarily used computers in use with a plurality of input-output devices (adaptor cards).